hw/arm/fsl-imx6ul.c: Remove dead SMP-related code

hw/arm/fsl-imx6ul.c: Remove dead SMP-related code

The i.MX6UL always has a single Cortex-A7 CPU (we set FSL_IMX6UL_NUM_CPUS
to 1 in line with this). This means that all the code in fsl-imx6ul.c to
handle multiple CPUs is dead code, and Coverity is now complaining that
it is unreachable (CID 1403008, 1403011).

Remove the unreachable code and the only-executes-once loops,
and replace the single-entry cpu[] array in the FSLIMX6ULState
with a simple cpu member.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Tested-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-id: 20190712115030.26895-1-peter.maydell@linaro.org